The present invention relates, in general, to a stent made of a shape-memory alloy and inserted into a stenosed vessel, or other part, and a stent foundation device for inserting such a stent into a desired part of a stenosed vessel and, more particularly, to a highly flexible and self-expandable stent used for being inserted into a stenosed vessel, such as a cancer-stenosed esophagus, biliary tract or urethra in addition to a thrombus-blocked vein, so as o artificially restore the stenosed vessel or being used in setting an artificial passage between intrajugular portal veins, the present invention also relating to a stent foundation device used for precisely inserting such a stent into a desired position within the stenosed vessel.
As we well known to those skilled in the art, blood veins may be stenosed, obstructed or blocked by thrombi or by arteriosclerosis, thus causing a variety of diseases.
In the case of such an angiostenosis, a stenosed vein may be surgically replaced with an artificial vein or may be surgically bypassed.
However, such a surgical operation for treating the angiostenosis is problematic in that it is necessary to but the body of a patent at a large area around stenosed veins and this undesirably leaves a large and ugly scar on the body. The conventional stenosis treating surgical operation also forces the patient to undergo recuperation for a substantially lengthy period of time, nevertheless, possibly failing to provide a desired operational effect.
Particularly, such angiostenoses have been typically caused by a hyperpiesia or heart disease. However, it is impossible to perform such a stenosis treating surgical operation on a patient having the hyperpiesia or the heart disease.
In an effort to overcome such problems derived from the surgical operation for treating the angiostenoses, a vascular restorative surgical operating procedure has been proposed to be used in place of such a conventional surgical operation. In such a vascular restorative surgical operating procedure, a femoral artery is perforated to form a small hole, through which a balloon catheter tube is inserted from the outside of the body of a patient into a desired stenosed part of the vein prior to expanding the balloon within the vein.
However, such a vascular restorative surgical operating procedure is problematic in that the restored vein is typically stenosed again within three or four months after the surgical operating procedure, thus forcing the surgical operating procedure to be repeatedly performed on the patient at three or four month intervals. This makes the patient repeatedly suffer from the surgical operating procedure and repeatedly pay much money for the surgical operating procedure, thus being very inconvenient to the patient.
On the other hand, in the case of an esophagostenosis caused by a cancer, it is impossible for the patient to ingest food through the stenosed esophagus, and so it is necessary to set an ingestion tube directly extending from the exterior of the abdomen into the stomach. However, this forces the patient and his family members to endure great physical hardship.
The conventional surgical operation or the conventional vascular restorative surgical operating procedure has been performed to treat biliary tract stenoses or urethra stenoses, or to set an artificial passage between intrajugular portal veins in addition to the treatment for the stenosed vein or stenosed esophagus.
However, the conventional surgical operation or the conventional vascular restorative surgical operating procedure for treating the stenoses regrettably fails to provide a desired operational effect and regrettably makes the patient and his family members experience great physical hardship while paying much money, thus being very inconvenient to them.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a stent, which is made of a superelastic shape-memory alloy and is semipermanently used when it is once set within a desired stenosed vessel of a patient.
Another object of the present invention is to provide a foundation device for such stents, which easily and effectively inserts and sets a stent into and within a desired part of a stenosed vessel of a patient""s body, thus restoring the stenosed vessel.
A further object of the present invention is to effectively set a stent within a desired part of a stenosed vessel, thus stretching and restoring the stenosed vessel.
Yet another object of the present invention is to allow a stent to be retracted into an outside tube so as to be reduced in volume and to be precisely reset at a desired position within a stenosed vessel when the stent fails to be precisely set at the desired position within the stenosed vessel.
Still another object of the present invention is to precisely set a stent at a desired position within the stenosed vessel.
Still another object of the present invention is to allow a stent to be semipermanently used when it is once set within a desired stenosed vessel of a patient.
In order to accomplish the above objects, the present invention provides a stent, consisting of a net-structural hollow cylindrical body made by knitting one longitudinal superelastic shape-memory alloy wire while repeatedly crossing the wire at various points so as to form a plurality of diamond-shaped meshes. The present invention also provides a foundation device for inserting such a stent into a stenosed vessel of a patient so as to restore the stenosed vessel. The foundation device consists of an actuation steel core, a movable tube and an insert tube, which are received within an outside hollow tube while being axially movable within the outside tube. In the above device, an insert tip is connected to the front end of the insert tube. The insert tip has a step forming a fitting end, at which the insert tip is partially fitted into the front end of the outside tube and is connected to the front end of the insert tube. A thread is fixed at one end thereof to the insert tube at a position spaced apart from m the step of the insert tip by a distance. The above thread holds the stent on the insert tube within the outside tube.